Cigarette butts are one of the most common waste on the planet and are not biodegradable, so they remain on the landscape for many years. Cigarette butt composition makes it suitable to be added during the manufacture of construction materials, so it can be considered a waste recovery material, helping to reduce the ecological footprint of the construction sector. This article shows the characterization of gypsum composites containing cigarette butt waste. Several gypsum specimens were prepared incorporating different percentages of cigarette butt waste (0.5%, 1.0%, 1.5%, 2.0% and 2.5%). Samples without waste additions were also prepared in order to compare the results obtained. Samples were tested for density, superficial hardness, flexural and compressive strength, bonding strength and acoustic performance. Results show that it is possible to add cigarette butts in a gypsum matrix, resulting in better mechanical behavior than traditional gypsums.

In this study, the limits of using the impedance tube, or Kundt tube, are examined using the two-microphone method to obtain the normal acoustic absorption coefficient when analyzing the sound absorption properties of lightweight acoustic fabrics. Lightweight porous fabrics with 3D microstructures that have been previously evaluated in reverberation chambers are used. For these materials, a test methodology will be developed in the impedance tube that aims to replicate the conditions of the tests carried out in the reverberation chamber. The samples are tested maintaining the same separation from the final rigid wall and are placed in the impedance tube in two different ways: first, exposing the flat samples to the wave, and second, in pleated format. The results show that it is not possible to consider the results obtained with both methodologies in samples of light textiles with three-dimensional microstructures to be the same. The similarity is limited to low frequencies (100–315 Hz) but bias, excessive dispersion of the data, different global results and shape indicators obtained suggest that both methods are not identical.

Information about the paper titled "CHALLENGE BASED ON PROFESSIONAL REALITY: FOCUSING ON COLLABORATIVE WORK AND MULTIDISCIPLINARY" at IATED Digital Library

Information about the paper titled "LEARNING IMPROVEMENT THROUGH TRAINING ITINERARIES IN THE INVERTED CLASSROOM METHODOLOGY" at IATED Digital Library

The reverberation time was tested in a reverberation chamber with three acoustic absorbent materials commonly used in construction. The tests were performed with different materials, setups, and back air layers. Results have been compared with those where this material is placed as a single piece. Analyzing obtained data, a linear regression model is established to predict, for certain frequencies, the alteration produced in the reverberation time. So, knowing the absorption coefficient of an amount of material, it is possible to predict the different absorption coefficients placing the same material in separated pieces and different distances from room walls. The model has been validated and tested, which demonstrates its accuracy, it has also been proved to be applicable to a wide variety of materials. It becomes a simple predictive tool that allows to estimate in situ the alteration in the reverberation time due to the separation of the absorbent material in patches.